Phosphorylguanidine esters

ABSTRACT

COMPOUNDS OF THE FORMULA:   (R-O-)2-P(=O)-NH-C(=NH)-NH-P(=O)(-O-R)2   IN WHICH R IS A C1-12 UNSUBSTITUTED ALIPHATIC HYDROCARBON RADICAL OR A C2-6 ALIPHATIC HYDROCARBON RADICAL HAVING ONE OR MORE HALOGEN AND/OR HYDROXYL SUBSTITUENTS ON THE 2-6 CARBON POSITIONS; AND COTTON OR RAYON FIBERS BEARING SUCH COMPOUNDS IN AN AMOUNT TO IMPART FLAME RETARDANCY TO THEM.

United States Patent O 3,634,555 PHOSPHORYLGUANIDINE ESTERS Fawzy G. Sherif, Cherry Hill, N.J., assignor to E. I. du

Pont de Nemours and Company, Wilmington, Del. 5 N0 Drawing. Filed July 31, 1969, Ser. No. 846,594 Int. Cl. C07f 9/24 US. Cl. 260-926 2 Claims ABSTRACT OF THE DISCLOSURE Compounds of the formula:

/" I IH i) OR This invention relates to tetra esters of diphosphorylguanidine and to their use for imparting fiamc-retardancy to cotton and rayon cellulosic fibers.

BACKGROUND Cellulosic fabrics are known to have poor resistance to burning in air. When a flame is applied to cellulosic fabrics while dry, they catch fire and quickly burn to ashes.

Compositions are known which when incorporated in cellulosic materials improve the resistance of those materials to burning. Such compositions usually have been, in part or in whole, heavily chlorinated organic compounds, compounds containing arsenic, antimony, bismuth, tin, zirconium or titanium in the molecule, phosphoric acid derivatives or combinations of these. Wagner et al., in US. Pat. No. 3,428,480 discloses the flame-retardancy treatment of cellulosic materials with a composition containing a phosphonium halide, a derivative of carbamicacid and other components.

Chief disadvantages of previous fire-retardant compositions include their high cost and tendency to produce stiffness or hardness in the fabrics when used in effective amounts.

'It is among the objects of this invention to produce novel compounds which will impart fire-retardancy to cellulosic fibers, specifically to cotton and rayon fabrics.

BRIEF SUMMARY OF THE INVENTION This invention concerns: (1) Tetra esters of diphosphorylguanidines of the general formula in which R is an aliphatic radical selected from C (preferably C unsubstituted aliphatic hydrocarbon radicals and C (preferably C aliphatic hydrocarbon radicals having one or more substituents in the 2 to 6 carbon positions (that is, the carbon atom linked to the phosphorus atom through oxygen should be free of such substituents) selected from hydroxyl, fiuoro, chloro and bromo; and

(2) cellulosic fibers selected from cotton and rayon bearing the subject novel compounds in proportions which impart flame-retardancy thereto.

DETAILED DESCRIPTION OF THE INVENTION The novel compounds of this invention are guanidine derivatives of the formula in which R is a C (preferably C aliphatic radical. The aliphatic radical can be a hydrocarbon radical, for instance a C saturated hydrocarbon radical such as methyl, butyl, hexyl or dodecyl, or an alkenyl radical such as allyl, isopropenyl, isobutenyl or octenyl. The aliphatic radical can also be a C hydrocarbon radical bearing one or more substituents selected from hydroxyl and halogen (fluorine, chlorine or bromine) groups. Such substituents should not be on the carbon atom linked to the phosphorus atom through oxygen. Exemplifying the substituted aliphatic radicals are 6-hydroxy-n-hexyl; 2-hydroxyethyl; Z-hydroxybutyl; 2-hydroxyl-4-chlorobutyl; 5- chlorohexyl; 2-chloroethyl; 2,3-dichloropropyl; and 2,3- dibromopropyl radicals. Other examples include the 2,3-dihydroxypropyl radical and fluorinated radicals such as 2,2, Z-trifluoroethyl and radicals of the structures (C1 CH; (CF CHCH and other branched fluorinated alkyl radicals.

The novel compounds of this invention are derived from bis-trichlorophosphoguanidine which can be prepared (as more fully described in my copending application Ser. No. 846,581, filed July 31, 1969) by reacting guanidine hydrochloride with two molar proportions of phosphorus pentachloride in an inert solvent such as chloroform or 1,2-dichloroethane under anhydrous conditions. The subject tetra esters of diphosphorylguanidine are prepared by reacting the bistrichlorophosphoguanidine with at least about six moles, per mole of the phosphoguanidine, of an alcohol, ROH, where R is as defined above. The enol of an enolizable ketone such as acetone, methyl ethyl ketone and the like can be regarded as an alcohol for the purpose of this invention. (Prior to reaction, an intimate mixture of reactants is produced at a low temperature to slow the reaction, and the reaction is then performed at an elevated temperature. Two moles of the alcohol reactant have their hydroxyl group replaced by chlorine, and where the resulting chlorides have sufficient vapor pressure they are evolved along with hydro gen chloride produced by the reaction. The reaction equation for producing the tetra esters can be thus shown generally as:

The resulting esters are viscous, transparent oils.

It has been found that these diphosphorylguanidine esters can be applied on cotton and rayon fibers or on blends of such fibers with other synthetic fibers such as polyethylene terephthalate to impart fiame-retardancy properties. Since these esters are oils, they allow fabrics made of such fibers to retain their desirable softness and hand after their application. However, because these are viscous oils, they are conveniently applied on fabrics from organic diluents such as chloroform, N,N-dimethylformamide, trichloroethylene, tetrachloroethylene, dimethylacetamide, dimethylsulfoxide and acetonitrile.

When the tetra (n-propyl) ester of diphosphorylguanidine is applied on cotton to the extent of 12% added weight, the treated. cotton requires a nitrogen-oxygen atmosphere containing above 28.9% oxygen by volume to support continued combustion of the cotton. Normal air contains only 21% oxygen by volume. Other tetra esters as defined produce similar flame-retardancy when applied on cotton or rayon fibers or fabrics. The minimum amount of the tetra ester borne by the fibers should be about 45% by weight, based on fiber weight, to impart significant flame-retardancy. For most commercial applications, about 9-10% add-on weight of the tetra ester compound is preferred, though this will vary somewhat depending on the R group.

These esters may also be incorporated in oil-based paints to provide paint films which when dry resist catching fire and which are self-extinguishing without afterglow when an applied flame is withdrawn from a flaming film.

The tetra esters of this invention also demonstrate a high conductivity at elevated temperatures in the range 200 -400 C. When incorporated in or coated on synthetic fibers such as linear polyamide or polyester fibers, they reduce the ability of such fibers to acquire static charges.

EXAMPLES The following examples illustrate the subject invention but are not in limitation thereof.

Parts are by weight unless otherwise stated.

Example l.--Bis-trichlorophosphoguanidine In a moisture-protected stirred reaction vessel, 95.5 parts guanidine hydrochloride and 416.5 parts phosphorus pentachloride were added to 1200 parts chloroform. The mixture was stirred and warmed until at 40 C. hydrogen chloride gas started to evolve. As formed, this gas was removed. The mixture was then stirred until the solids went into solution. Four hours were required. 15.7 parts acetonitrile was added to the mixture, followed by 66 parts n-hexane, and the mixture was left for an hour. Crystals of product separated out. The crystals had a melting point of 131 C. They were soluble in chloroform, acetonitrile and dichloroethane. They were insoluble in carbon tetrachloride, benzene, n-hexane, ethyl ether and petroleum ether. They reacted rapidly with water, acetone and alcohols with the evolution of hydrogen chloride. When left in open air, they evolved hydrogen chloride.

The crystals were analyzed and gave the following results:

Percent calculate HN C13P=NCN=P 013 EXAMPLE 2 95.5 parts guanidine hydrochloride and 416.5 parts chloroform as in Example 1. The reacted mass was then externally ice-cooled. During two hours while ice-cooled, 600 parts trifluoroethyl alcohol were added dropwise to the reacted mass. The ice bath was then replaced by heating means, and the mixture was refluxed for 16-18 hours. Gases, including hydrogen chloride, were evolved during reflux, some of which were condensed'in an ice bath cooled trap. The condensed gas had the infrared spectrum and boiling point of l,l,l-trifiuoro-Z-chloroethane.

When no more hydrogen chloride was evolved, the reaction mass was distilled to remove chloroform, leaving a viscous oil. This oil was heated at 100 C. under vacuum to remove traces of chloroform and hydrogen chloride. This product was a transparent heavy oil, obtained in almost quantitative yield. Analysis of this oil showed Percent Percent calculated found asOnHnOoNaFrzPz Carbon 19. 63 19. 75 Hydrogen 2. 30 2. 02 Nitro 8. 93 7. 68 Phosphorus 10. 12 11. 32 Halogen 41. 87 41. 66

This compound was soluble in chloroform and in acetonitrile. It boiled at 300 C. without decomposition.

The infrared spectrum and the P nuclear magnetic resonance spectrum of this compound indicated its structure as Percent calcu- Pereent lated as C13- found HMOONQPZ This product was soluble in chloroform and in methanol. It could be heated at 225 C. at atmospheric pres sure or at 100 C. under vacuum without decomposition.

The infrared spectrum and the P nuclear magnetic resonance spectrum of this compound indicated its structure to be II 0 NH 0 EXAMPLE 4 The procedure of Example 2 was followed except that 372 parts ethylene glycol were used instead of the trifluoroethyl alcohol. Ice-condensed gases from the ethylene glycol reaction had the infrared spectrum and boiling point of ethylene chlorohydrin. The product was a transparent heavy oil having the following analysis:

Percent Percent calculated found as C9H2aO1oNsPz This product was soluble in chloroform. It could be phosphorus pentachloride were reacted in 1200 parts 75 heated at 250 C. in open air without decomposition.

The infrared spectrum and the P NMR spectrum of the compound indicated its structure to be In a moisture-protected stirred reaction vessel, 88 parts of the product of Example 1 were dissolved in 375 parts chloroform. While the vessel was cooled with ice, 348 parts allyl alcohol was added dropwise during one hour. Hydrogen chloride was given off by the mixture. The mixture was then heated atreflux for four hours.

The mixture was then distilled to remove chloroform. No hydrogen chloride was evolved during this distillation. When most of the chloroform was removed, the remaining material was distilled at 20 mm. Hg pressure at room temperature. 66 parts of viscous colorless oil was obtained. This oil was analyzed and compared with the calculated analysis of the tetraallyl ester:

Percent Percent calculated found as CuHuOsNsPz A cotton fabric was soaked in a 5% solution of the product of Example 2 in chloroform, withdrawn and dried at 100 C. The treated fabric was exposed to a direct flame for two seconds. Only the edges of the fabric charred and the flame at the edges of the fabric self-extinguished as soon as the fabric was removed from the flame. When a like cotton fabric was similarly treated and exposed to a direct flame for 30 seconds, it charred slowly, stayed intact and did not ash. No after-glow occurred in either treated fabric.

A similar cotton fabric without treatment was exposed to similar direct flame for 2 seconds. The fabric caught the flame and turned to ashes.

EXAMPLE 7 Flame-retardancy test 18 parts of the product from Example 3 were dissolved in 27 parts N,N-dimethylformamide.

A 5 inch by inch strip of cotton twill was padded in the solution and squeezed in a roller. It was dried 3 minutes at 130 C. and then heated 3 minutes at 165 C. The gain in weight by the fabric at this point was 26%. The fabric was not discolored and it was very soft.

The treated fabric was spread in a vertical plane and supported along its vertical edges. The spread fabric was positioned in a transparent column open only at the top. The top of the column was six or more inches above the spread fabric. The interior of the column was provided with an upward flow from its base of a gaseous mixture of pure oxygen and pure nitrogen. The volume flow rate of each gas making up the mixture was instrumented and manually adjustable.

With gas mixture flowing, the top of the spread fabric was ignited from the top. The flow rates of the oxygen and nitrogen were adjusted until the flame on the ignited fabric just went out. The ratio of the volume flow of oxygen to the sum of the volume flows of oxygen and nitro- 6 gen point at this point was then determined. This value, called the Limiting Oxygen Index or LOI, was 0.325 for this fabric.

When identical fabric was treated with a solution of 9 parts of the product of Example 3 in 36 parts dimethylformamide in similar fashion, the fabric gained 12% in weight. That sample gave an LOI of 0.289.

Identical fabric untreated gave an LOI of 0.180.

EXAMPLE 8 The procedure of Example 2 was repeated except that 1307 parts 2,3-dibromopropyl alcohol were used instead of the trifluoroethyl alcohol. One of the gaseous reaction products was l-chloro-2,3-dibromopropane. The product was a transparent heavy oil. The infrared spectrum of the product is typical of a tetra ester of the formula This product was tested for flame-retardancy effectiveness by the procedures of Example 7. Cotton twill having a 24% add-on weight of this product showed an LOI of 0.322, and such fabric with an 11.7% add-on weight showed an LOI of 0.266.

The product was also tested for flame-retardancy on fabric made from fibers consisting of polyethylene terephthalate fibers blended with 20% by weight cotton fibers. At an add-on weight of 30%, the LOI was 0.293. At an add-on of 14%, the LOI was 0.256. The untreated fabric had an LOI of 0.175.

EXAMPLE 9 The procedure of Example 2 was followed except that 1125 parts of n-dodecanol were used instead of the trifluoroethyl alcohol. N-dodecyl chloride was one of the reaction products and this was removed when the chloroform was distilled off. The product was a heavy oil having an infrared spectrum typical of an ester of the formula The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described, for obvious modifications will occur to those skilled in the art.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Compounds of the formula RO O NH 0 0R wherein R is an aliphatic radical selected from C unsubstituted hydrocarbon radicals and C hydrocarbon radicals having one or more substituents on the 2 to 6 carbon positions selected from hydroxyl, fluoro, chloro and bromo.

2. Claim 1 wherein R is selected from CH CF -CH CH CH --CH CH OH, CH CHBrCl-I Br and 12 25- References Cited UNITED STATES PATENTS 2,574,517 11/1951 Walter et al. 260926 2,944,075 7/1960 Debo 260927 X CHARLES B. PARKER, Primary Examiner R. L. RAYMOND, Assistant Examiner US. Cl. X.R. 

